Acura 1994 Integra Service Manual page 614

Pressure Control
Low assist at higher speeds:
When steering resistance is low. such as when driving at high speeds. or when driving straight ahead, the input shaft is
near or in the neutral position, so there is little or no flow to any of the power cylinder orifices, Most of the feed pressure
trom the pump is bypassed to the reservoir. Because of this, the pressure stays the same in both sides of the power cylin-
der, resulting in low or no assist.
v
az =- S
\->/
-\7/
RETURN PASSAGE
(To RESERVOIRI
VALVE UNIT
<sEcnoN A-A>
INPUT SHAFT
High assist at lower speeds:
When steering resistance is high, such as when driving at low speed, or when turning the wheel with the car stopped, the
difference in angle created between the input shaft and the valve opens the fluid passage on one side, and closes the fluid
passage on the other side, at each pair of orifices. The fluid pressure increases in the side of the power cylinder fed by the
larger fluid passage. This increased pressure pushes on the rack piston, allowing the steering wheel to be turned with light
effon. On the other side of the power cylinder, the return passage opens allowing the steering fluid to return through the
input shaft to the reservoir. The fluid passages to the power cylinder automatically change in size, increasing as the steer-
ing resistance increases. In other words, the passages become larger and power assist increases when the steering effort
would normally be high, (for example. when parking or making low speed turns). and the passages become smaller and
power assist decreases when the steering effort would normally be low, (for example, when driving at high speeds or
straight ah€ad).
FLUIO PASSAGE TO
POWER CYLINDER
From PUMP
A
/t-:\
v"
=iJ
RETURN
PASSAGE
FLUID PASSAGE FROM
POWER CYLINDER
ALVE
F.om PUMP
RESERVOIR
<SECTION A.A>
17-9